1. Field of the Invention
The present invention relates to a method and circuit means or a circuit arrangement for minimizing interference or noise, especially in electronic circuits, which are exposed to stray or scattered electromagnetic radiation, and particularly in which symmetrical measured signals are analyzed or evaluated.
2. Related Art
Generally the requirements for integrated circuits regarding robustness against stray electromagnetic radiation are continuously increasing with concurrent increases in the integration density of these circuits. The foreseeable contingent fixed integration of capacitors of larger capacitance for broadband filtering of electromagnetic interference in circuits leads however to increased costs when small structure widths are used and thus should be avoided.
Amplification and conditioning of signals, especially small signals, is required in circuit applications, especially in sensors. The measurement of the output signal from a Wheatstone bridge circuit in a resistively operating pressure sensor, as described for example in DE 196 03 674.7 A1, is one example of this sort of sensor circuit application.
In this sort of application input signals in a range of a few μV are corrected and amplified by a factor larger than 100. At the same time great robustness against stray or scattered electromagnetic radiation, which can lead to difference signals with insufficient symmetry on the input side of the integrated circuit is required. The amplitude of this stray radiation very closely approaches that of the actual measured variable and thus can impair the functioning of the sensor.